Newb with a 225 needs assistance
Metal-on-metal grinding is definitely bad. Without more specificity it's impossible to diagnose remotely (even a youtube video with the sound audible would help). Could be any number of different things. If you're really lucky it's a faulty alternator bearing or something of that nature.
Oil pressure light should not be on, but it doesn't necessarily mean the pump or the engine is bad. If the sender is faulty or the wire is chafed, the light will go on. It will also be a good idea to service the oil pressure relief valve to make sure it's doing its job, as described in these two threads:
thread 1,
thread 2.
As quickly as you can, get the three books described in
this thread.
Tune-up parts and technique suggestions in
this thread. Carburetor operation and repair manuals and links to training movies and carb repair/modification threads are posted
here for free download. You'll want to do the
Fuel line mod and eventually you may want to do the
HEI upgrade as well.